1. Field of the Invention
The present invention relates to amorphous silica and active analcime having a novel particulate shape, and a process for the preparation thereof. More particularly, the present invention relates to a process for preparing active analcime or amorphous silica from an analcime type zeolite.
2. Description of the Prior Art
Synthetic analcime is a known substance, and it is known that this substance can be obtained by subjecting silica, caustic alkali and aluminum hydroxide or an aluminate at a ratio corresponding to the composition of analcime to hydrothermal reaction.
It also is known that synthetic analcime having a sharp particle size distribution is valuably used as a filler for cosmetics, a filler for paints, an antiblocking agent for films, a carrier for liquid chromatography and a spacer for liquid crystals (see, for example, Japanese Patent Application Laid-Open Specification No. 186413/85).
However, synthetic analcime is composed of extremely inactive inorganic particles. For example, the BET specific surface area of synthetic analcime is smaller than 5 m.sup.2 /g and the moisture absorption determined under conditions of a relative humidity of 90%, an ambient temperature of 25.degree. C. and a standing time of 48 hours is zero or substantially zero.
There are various application objects of fillers or filling materials used for various products of resins, rubbers, papers, oils, detergents and cosmetics, and in many cases, particles of the fillers or filling materials are required to have at least a certain surface activity. For example, this surface activity is necessary for preventing migration of additives in a resin or rubber or for absorbing an ink in case of paper.